Elsevier

Ophthalmology

Volume 119, Issue 9, September 2012, Pages 1744-1753
Ophthalmology

Original article
Blindness and Visual Impairment in an Urban West African Population: The Tema Eye Survey

https://doi.org/10.1016/j.ophtha.2012.04.017Get rights and content

Objective

To determine the prevalence, causes, and risk factors of blindness and visual impairment among persons aged 40 years or older residing in an urban West African location.

Design

Population-based, cross-sectional study.

Participants

A total of 5603 participants residing in Tema, Ghana.

Methods

Proportionate random cluster sampling was used to select participants aged 40 years or older living in the city of Tema. Presenting distance visual acuity (VA) was measured at 4 and 1 m using a reduced logarithm of the minimum angle of resolution tumbling E chart and then with trial frame based on autorefraction. A screening examination was performed in the field on all participants. Complete clinical examination by an ophthalmologist was performed on participants with best-corrected visual acuity (BCVA) <20/40 or failure of any screening test.

Main Outcome Measures

Age- and gender-specific prevalence, causes, and risk factors for blindness (VA of <20/400 in the better eye, World Health Organization definition) and visual impairment (VA of <20/40 in the better eye).

Results

A total of 6806 eligible participants were identified, of whom 5603 (82.3%) participated in the study. The mean age (± standard deviation) of participants was 52.7±10.9 years. The prevalence of visual impairment and blindness was 17.1% and 1.2%, respectively. After refraction and spectacle correction, the prevalence of visual impairment and blindness decreased to 6.7% and 0.75%, respectively, suggesting that refractive error is the major correctable cause of visual impairment and blindness in this population. Of 65 subjects with a VA <20/400, 22 (34%) were correctable with refraction, 21 to the level of visual impairment and 1 to normal. The remaining 43 patients (66%) had underlying pathology (cataract in 19, glaucoma in 9, nonglaucomatous optic neuropathy in 3, corneal opacities in 3, retinal disease in 3, and undetermined in 5) that prevented refractive correction. Increased age was a significant risk factor for blindness and visual impairment.

Conclusions

There is a high prevalence of blindness and visual impairment among those aged ≥40 years in Tema, Ghana, West Africa. Refractive error is a major cause of blindness and visual impairment in this population, followed by cataract, glaucoma, and corneal disease.

Financial Disclosure(s)

The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Section snippets

Study Population

Tema is a city of the Greater Accra region in Ghana, West Africa. Approximately 17.6% of Ghana's population lives in the Greater Accra region,11, 12 despite the fact that this is the geographically smallest of Ghana's 10 regions. The 2005 estimated population in the Tema District was 562 291, extrapolated from census data from 200012 and known birth and death rates. As one of the busiest ports in West Africa, Tema has attracted workers from all over Ghana, making it an ethnically and

Results

There were a total of 230 clusters identified for sampling in the 5 communities. Thirty-seven of these were randomly chosen, the number of clusters from each community (and therefore, the number of subjects) proportionate to the estimated number of people aged 40 years or older residing in each community. The house-to-house census enumerated 6806 eligible subjects, of whom 5603 came for the field examination for a participation rate of 82.3%. The field examination identified 1869 subjects

Discussion

The TES is one of only a few population studies of blindness, visual impairment, and eye diseases in West Africa and perhaps the only one that has studied a purely urban population. We found a high prevalence of curable vision loss due to uncorrected refractive error or cataract. The percentage of curable visual impairment from refractive error or cataract was 39.2%, and the percentage of curable blindness from these causes was 58.3%. In addition, preventable vision loss from glaucoma was found

Acknowledgments

The authors thank Pak Sang Lee of the National Institute for Health Research Biomedical Research Centre for Ophthalmology, UCL Institute of Ophthalmology, and Moorfields Eye Hospital, London, England, who provided technical training and support for this study.

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    Manuscript no. 2011-40.

    Financial Disclosure(s): The author(s) have no proprietary or commercial interest in any materials discussed in this article.

    Supported by grants to International Aid (Spring Lake, MI) from Pfizer, Inc., the Allergan Foundation, Mid-Career Physician Scientist Award from the American Glaucoma Society (Dr. Budenz), National Institutes of Health, National Eye Institute Training Grant T32EY-07127, Clinical Trials Training Program in Vision Research (Dr. Whiteside-de Vos).

    *Group members of the TES Study Group are listed online (available at http://aaojournal.org).

    A list of members of the TES Study Group is available at http://aaojournal.org.

    Dr. Whiteside-de Vos was not affiliated with the Johns Hopkins Bloomberg School of Public Health while conducting study activities in Ghana.

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